In the pancreatic beta cell and liver parenchymal cells the main plasma membrane glucose transporter is GLUT2. Under physiological glucose concentrations the rate at which GLUT2 transports glucose across the membrane is not rate limiting to the overall rate of glucose uptake in these cells. The rate of glucose uptake is limited by the rate of phosphorylation of glucose to glucose-6-phosphate (G-6-P) which is catalysed by glucokinase (GK). GK has a high (6-10 mM) Km for glucose and is not inhibited by physiological concentrations of G-6-P. GK expression is limited to a few tissues and cell types, most notably pancreatic beta cells and liver cells (hepatocytes). In these cells GK activity is rate limiting for glucose utilization and therefore regulates the extent of glucose induced insulin secretion and hepatic glycogen synthesis. These processes are critical in the maintenance of whole body glucose homeostasis and both are dysfunctional in diabetes.
The compounds of the present invention are GK agonists, and are therefore believed to be useful in the treatment of diabetes, obesity, glaucoma, osteoporosis, cognitive disorders, immune disorders, depression, hypertension, and metabolic diseases.